As many as 95,000 employees in the West Midlands - and almost a million across Britain - were on sick leave for more than a month over the past three years.
The government has revealed the new figures between October 2010 and September 2013, as it prepares to launch a new Health and Work Service to combat the problem.
It shows more than 130 million days are still being lost to sickness absence every year in Great Britain and working-age ill health costs the British economy £100billion a year.
Minister of State for Work and Pensions, Mike Penning, said: “More than 130 million days a year are lost to sickness absence in Great Britain, which has a substantial impact on workers, employers and taxpayers.
“As part of the government’s long-term economic plan, we are taking action to get people back into work. This is a triple-win.”